The purpose of blockchain is to make a safe and direct connection between buyers and sellers when making transactions without the need of the middleman (in most cases the banks). The term Blockchain comes from a block which is a record of new transactions and a chain which is the place where the block is added.
When John wants to send a transaction to Catherine it looks as follow:
1. John makes a request to send money to Catherine
2. The transaction is recorded on the block
3. The block is distributed to every party in the network
4. Those in the network approve that the transaction is valid
5. The block is added to the chain and the transaction makes a permanent and transparent record
6. Catherine receives the payment